Exam 3: Lecture 36

Question 1

What is osmoregulation?

Answer 1

The process of maintaining body fluid osmolarity

Question 2

What is the normal range for osmolarity?

Answer 2

290-300 mOsm/L

Question 3

In the body’s response to water deprivation, what factor stimulates the osmoreceptors in the anterior hypothalamus?

Answer 3

An increase in plasma osmolarity

Question 4

What hormone binds to the principal cells to increase water reabsorption?

Answer 4

ADH

Question 5

What is the end result the body produces to combat water deprivation?

Answer 5

Water reabsorption increases, urine osmolarity increases, urine volume decreases

Question 6

In response to water drinking, ADH is (Inhibited/secreted)?

Answer 6

Inhibited

Question 7

What is the end result from the body’s response to drinking water?

Answer 7

Urine osmolarity decreased, urine volume increased

Question 8

What is the corticopapillary osmotic gradient?

Answer 8

Gradient of osmolarity in the interstitial fluid of the kidney - extends from cortex to papilla

Question 9

Is the osmolarity greater in the cortex or medulla?

Answer 9

Medulla

Question 10

What are the two mechanisms that help create the corticopapillary osmotic gradient?

Answer 10

• Countercurrent multiplication in the Loop of Henle
• Urea recycling in the collecting ducts located in the inner medulla

Question 11

When water reabsorption increases, what happens to urine osmolarity and urine volume?

Answer 11

Osmolarity increases, volume decreases

Question 12

The (cortical/juxtamedullary) mephron is mostly responsible for concentrating urine

Answer 12

Juxtamedullary

Question 13

The osmolarity of the tubular fluid and interstitial fluid must do what to maintain the interstitial osmotic gradient?

Answer 13

Mirror each other

Question 14

Is the thin descending limb permeable to water, solutes, or both?

Answer 14

Water

Question 15

Is the thin ascending and thick ascending limbs permeable to water, solutes, or both?

Answer 15

Solutes

Question 16

If there is an increase in ADH, what happens to the osmolarity of the interstitium?

Answer 16

Increase osmolarity

Question 17

What are the main solutes deposited into the interstitium through the Loop of Henle?

Answer 17

Na, Cl, and K

Question 18

The concentration of the tubular fluid at the hairpin turn is dependant on what factor?

Answer 18

The length of the loop

Question 19

The length of the Loop of Henle determines what?

Answer 19

Maximal urine concentration

Question 20

What is the first step in countercurrent multiplication?

Answer 20

NaCl leaves ascending limb, goes to interstitial fluid

Question 21

Countercurrent exchange is a (passive/active) process

Answer 21

passive

Question 22

The capillaries associated with juxtamedullary nephrons and serve medulla and papilla of kidney are called what?

Answer 22

Vasa recta

Question 23

Blood leaving in ascending limb of vasa recta will take some of the solutes where?

Answer 23

Away from the osmotic gradient

Question 24

Within the vasa recta, when the solutes are exposed to higher osmolarity in the descending limb which way do they move?

Answer 24

The solutes will enter the blood

Question 25

After the blood leaves the vasa recta, why will some solutes enter the systemic circulation?

Answer 25

The blood leaving will have a slightly higher osmolarity than the blood entering

Question 26

Which part of the Loop of Henle is permeable to water?

Answer 26

Thin descending limb